Combine opencode-container and claude-container into a unified agent-container

Merge the two separate container projects into a single image and
management script. Both OpenCode and Claude Code are installed in the
same Arch Linux image and share one persistent $HOME directory, which
enables the opencode-claude-bridge plugin to read Claude CLI credentials
from within OpenCode.

Subcommands: opencode, claude, update, force-cleanup.

Dockerfile

@@ -0,0 +1,40 @@
+FROM archlinux:latest
+
+ARG USERNAME=dev
+ARG UID=1000
+ARG GID=1000
+
+RUN pacman -Syu --noconfirm \
+        base-devel \
+        git \
+        ca-certificates \
+        bash \
+        less \
+        ripgrep \
+        nodejs \
+        npm \
+        curl \
+        sudo && \
+    groupadd -g ${GID} ${USERNAME} && \
+    useradd -m -u ${UID} -g ${GID} -s /bin/bash ${USERNAME} && \
+    echo "${USERNAME} ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers && \
+    pacman -Scc --noconfirm
+
+# Install OpenCode from AUR
+WORKDIR /tmp
+USER ${USERNAME}
+
+RUN git clone https://aur.archlinux.org/opencode-bin.git && \
+    cd opencode-bin && \
+    makepkg --syncdeps --noconfirm --install && \
+    sudo rm -rf /tmp/opencode-bin && \
+    sudo pacman -Scc --noconfirm
+
+# Install Claude Code using the native installer, then copy the binary
+# to a system-wide location so it survives the home directory bind mount
+RUN curl -fsSL https://claude.ai/install.sh | bash && \
+    sudo cp ~/.local/bin/claude /usr/local/bin/claude && \
+    rm -rf ~/.local/share/claude ~/.local/bin/claude ~/.claude ~/.claude.json \
+           ~/.cache/claude
+
+WORKDIR /home/${USERNAME}